Traffic Condition and Emission Factor from Diesel Vehicles within the Kathmandu Valley

Abstract

Past research on air quality within the Kathmandu Valley indicates that diesel vehicles make a substantial contribution to the ambient pollution. Hence, it's important to identify cost-effective measures for reducing their emissions. As a first step, roadside observations of diesel vehicles were recorded between February and April 2017 at six locations: two on the ring road (RR), two inside the RR, and two on major arterial highways outside the RR. Out of all diesel vehicles observed (n = 12,039), 35% were emitting a visible plume of black smoke and hereafter are referred to as "superemitters". Of the 4,248 superemitters, 45% were buses of varying sizes, 34% were large trucks, and 19% were small pickups. Superemitters made up the largest fraction of diesel vehicle traffic on the RR (43%-46%) but were also abundant inside the RR (27%-29%), where human population and pollutant exposure is greatest. Upon developing a comprehensive understanding of the superemitting vehicle types and ownership, maintenance patterns and servicing costs were studied through a survey of vehicle owners, vehicle drivers, and local maintenance centers. The costs of general servicing ranged between USD 16 for tractors and USD 203 for construction vehicles depending on the size of the vehicle. Lastly, the effect of general servicing on emissions while idling was explored for a small sample of superemitters (n = 4). PM 2.5 emissions reduced from 10.90 g L-1 to 3.76 g L-1 and BC emissions reduced from 0.847 g L-1 to 0.596 g L-1 after servicing. Taken together, results from this roadside surveillance study and exploratory emission-measurement campaign provide preliminary evidence that a policy of mandatory, routine maintenance of a targeted subset of the diesel fleet can systematically reduce emissions and improve air quality in the Kathmandu Valley and other cities around the world that are facing similar problems.

Estimating Emission Load from Road Transportation within the Bhaktapur Municipality, Nepal

“…This study does not incorporate the latest emission factors published in the year of 2019 [ 35 ] nor did it address the relations between emission factors obtained during idling and running conditions of vehicles based on field measurement [ 25 ] potent to bring more accuracy in emission estimation to this study. Emission factors used in this study were static and do not consider its changes in nature due to surrounding environmental conditions, speed of vehicles, and age of vehicles.…”

Flow physics of air pollutants dispersion: A case study in an urban street canyon in Baghbazar, Kathmandu

“…Kathmandu, with a growing population density, witnesses over 25% of Nepal's registered vehicles, a major contributor to its air pollution [2] [3] [4]. Many vehicles use poor-quality fuel, are old, and lack maintenance, exacerbating emissions [5]. Other significant sources include industrial activities and residential heating practices.…”

Assessment of Environmental Policies and Institutions for Effective Air Quality Management in Nepal

“…According to a report published by Yale University, Nepal was ranked the third-highest polluted country in the world in air quality (EPI, 2020). Vehicular emissions in the cities of Nepal are comparatively higher than in other developing cities (Byanju et al, 2012;Mool et al, 2019) suggesting the potential sizable health risk (Gurung & Bell, 2012;Pratali et al, 2019). With the rapid, uncontrolled and unmanaged developmental projects and urbanization, air pollution has increased in Nepal; victimizing people with serious airborne diseases (K. Bhattarai & Conway, 2021;Kurmi et al, 2016;Manisalidis et al, 2020).…”